Problem: Simplify the following expression: $z = \dfrac{5}{y} \div \dfrac{2}{8y}$
Answer: Dividing by an expression is the same as multiplying by its inverse. $z = \dfrac{5}{y} \times \dfrac{8y}{2}$ When multiplying fractions, we multiply the numerators and the denominators. $z = \dfrac{ 5 \times 8y } { y \times 2}$ $z = \dfrac{40y}{2y}$ Simplify: $z = \dfrac{20}{1}$